3 Microbial Endophytes: Sustainable Approach …
47
ORE35). Isolate ORE35 was the most potential P solubilizers among all these endophytic isolates. Three promising isolates were identified by 16S rRNA sequencing
for instance from chickpea nodules B. subtilis strain CNE215; whereas roots have B.
licheniformis strain CRE1; in case of wheat root B. flexus strain WRE 20. B. methylotrophicus strain CKAM was selected from the root endosphere of healthy apple
trees based on higher P-solubilization (687 mg/L) and other plant growth-promoting
attributes (Mehta et al. 2014).
Five rhizospheric and two root endophytic actinobacteria were isolated from wheat
plants (Jog et al. 2014). Maximum phosphate solubilizing activity in tricalcium phosphate supplemented medium was exhibited by actinobacterial isolate Streptomyces
mhcr 0816. Zhao et al. (2015) isolated 48 endophytic bacteria from surface-sterilized
tissues of the medicinal plant Lonicera japonica wherein few isolates showed a
zone of phosphate solubilization on the Pikovskaya agar medium. These bacterial
strains were identified as Paenibacillus and Bacillus strains. Pandya et al. (2015)
isolated 26 non-rhizobial and one fungal endophyte from Vigna radiata root nodules
and only 11 endophytes solubilized phosphate. Maximum phosphorus solubilization
was observed in Paenibacillus xylanilyticus strain M15 (134.483 μg ml
−1 ). The free
phosphate release ranged from 37.4 μg ml
−1 in strain M13 to 134.48 μg ml
−1 in the
strain M15. However, free phosphate released by strain M15 was significantly lower
than free phosphate released by the endophyte B. cereus strain P31 (354.3 μg ml
−1 )
isolated from potato roots (Dawwam et al. 2013). The most efficient phosphate solubilizing strains belong to species of Klebsiella (M13), Dyadobacter, Blastobacter,
Bacillus, and Paenibacillus spp.
Bacterial endophytes were also isolated and characterized from the root and shoot
tissues of Lavandula dentate plants growing under organic management (Pereira
et al. 2016). These were identified as Pseudomonas brassicacearum subsp. neoaurantiaca, Pseudomonas moorei, Variovorax soli, Pseudomonas frederiksbergensis, Pseudomonas fuscovaginae, B. cereus, Bacillus aerophilus, Bacillus drentensis, Pseudomonas graminis, Bacillus aryabhattai, and Pseudomonas lutea. The higher bacterial diversity of endophytes was observed in roots having to six different genera
(Pseudomonas, Variovorax, Rhizobium, Caulobacter, Bacillus, and Paenibacillus),
while in shoots, 91% of the endophytic isolates were characterized and identified
as Bacillus and Pseudomonas, whereas only one belongs to genus Xanthomonas.
Matos et al. (2017) isolated 40 endophytic bacterial isolates from banana tree roots.
Approximately 67.5% of the isolates solubilized phosphorus from soy lecithin. Acid
phosphatase activity was detected in 65% of the isolates and Aneurinibacillus sp.
and Lysinibacillus sp. isolates showed the best solubilization indexes. Bacillus sp.
isolate EB78 exhibited P solubilization capacity in solid media when Ca 3 (PO 4 ) 2 and
soy lecithin were used as P sources. This isolate significantly reduced the pH of the
liquid medium and exhibited acid phosphatase activity.
The salt-tolerant endophytic and phosphate solubilizing bacterial isolates Acinetobacter sp. ACMS25 and Bacillus sp. PVMX4 was isolated from Phyllanthus amarus
(Govindasamy et al. 2018). These isolates showed a higher zone of clearance and
solubilization index when compared with standard B. megaterium strain MTCC446 in
the presence of 160 mM NaCl (Chen et al. 2006; Tao et al. 2008; Verma et al. 2013).
47
ORE35). Isolate ORE35 was the most potential P solubilizers among all these endophytic isolates. Three promising isolates were identified by 16S rRNA sequencing
for instance from chickpea nodules B. subtilis strain CNE215; whereas roots have B.
licheniformis strain CRE1; in case of wheat root B. flexus strain WRE 20. B. methylotrophicus strain CKAM was selected from the root endosphere of healthy apple
trees based on higher P-solubilization (687 mg/L) and other plant growth-promoting
attributes (Mehta et al. 2014).
Five rhizospheric and two root endophytic actinobacteria were isolated from wheat
plants (Jog et al. 2014). Maximum phosphate solubilizing activity in tricalcium phosphate supplemented medium was exhibited by actinobacterial isolate Streptomyces
mhcr 0816. Zhao et al. (2015) isolated 48 endophytic bacteria from surface-sterilized
tissues of the medicinal plant Lonicera japonica wherein few isolates showed a
zone of phosphate solubilization on the Pikovskaya agar medium. These bacterial
strains were identified as Paenibacillus and Bacillus strains. Pandya et al. (2015)
isolated 26 non-rhizobial and one fungal endophyte from Vigna radiata root nodules
and only 11 endophytes solubilized phosphate. Maximum phosphorus solubilization
was observed in Paenibacillus xylanilyticus strain M15 (134.483 μg ml
−1 ). The free
phosphate release ranged from 37.4 μg ml
−1 in strain M13 to 134.48 μg ml
−1 in the
strain M15. However, free phosphate released by strain M15 was significantly lower
than free phosphate released by the endophyte B. cereus strain P31 (354.3 μg ml
−1 )
isolated from potato roots (Dawwam et al. 2013). The most efficient phosphate solubilizing strains belong to species of Klebsiella (M13), Dyadobacter, Blastobacter,
Bacillus, and Paenibacillus spp.
Bacterial endophytes were also isolated and characterized from the root and shoot
tissues of Lavandula dentate plants growing under organic management (Pereira
et al. 2016). These were identified as Pseudomonas brassicacearum subsp. neoaurantiaca, Pseudomonas moorei, Variovorax soli, Pseudomonas frederiksbergensis, Pseudomonas fuscovaginae, B. cereus, Bacillus aerophilus, Bacillus drentensis, Pseudomonas graminis, Bacillus aryabhattai, and Pseudomonas lutea. The higher bacterial diversity of endophytes was observed in roots having to six different genera
(Pseudomonas, Variovorax, Rhizobium, Caulobacter, Bacillus, and Paenibacillus),
while in shoots, 91% of the endophytic isolates were characterized and identified
as Bacillus and Pseudomonas, whereas only one belongs to genus Xanthomonas.
Matos et al. (2017) isolated 40 endophytic bacterial isolates from banana tree roots.
Approximately 67.5% of the isolates solubilized phosphorus from soy lecithin. Acid
phosphatase activity was detected in 65% of the isolates and Aneurinibacillus sp.
and Lysinibacillus sp. isolates showed the best solubilization indexes. Bacillus sp.
isolate EB78 exhibited P solubilization capacity in solid media when Ca 3 (PO 4 ) 2 and
soy lecithin were used as P sources. This isolate significantly reduced the pH of the
liquid medium and exhibited acid phosphatase activity.
The salt-tolerant endophytic and phosphate solubilizing bacterial isolates Acinetobacter sp. ACMS25 and Bacillus sp. PVMX4 was isolated from Phyllanthus amarus
(Govindasamy et al. 2018). These isolates showed a higher zone of clearance and
solubilization index when compared with standard B. megaterium strain MTCC446 in
the presence of 160 mM NaCl (Chen et al. 2006; Tao et al. 2008; Verma et al. 2013).